The present invention relates to a data communication device, and more particularly to a data communication device provided with unit for generating transfer data having an identification code and another unit for identifying the kind of received data based on the identification code thereof.
Conventionally, there has been known a First-In-First-Out type buffer (hereinafter referred to as a FIFO) as a buffer to be provided between a plurality of data communication devices. Transfer data to be stored in the buffer is 9-bit data formed by adding a parity bit to 8-bit (1-byte) information data or command data.
Furthermore, there has been known a packet transfer method as a method for transferring a great mass of data. According to the packet transfer method, data to be transferred are divided into a number of small groups which are in turn transferred by the packet.
According to the conventional method for transferring the 9-bit data, when transferred data is received, a bit pattern of the data is collated with a predetermined bit pattern so as to discriminate whether the received data is command data or information data. Accordingly, when a great mass of data are received, it takes much time to identify the kind of each data. Thus, a throughput of the data communication device will be lowered.
When some of data transferred in a great mass are damaged during a transfer process, for example, information data is distorted into command data, the subsequent data cannot normally be received. Consequently, the predetermined data processing may not be carried out.
On the other hand, according to the packet transfer method, a header is added to each packet. Accordingly, when some of the data being transferred is damaged, although all the data in the packet including the damaged data are damaged, data of the other packets are not subject to the damage caused by the damaged data. However, the addition of the header to each packet inevitably increases the number of data to be transferred.